1. Field of the Invention
This invention relates to novel Schiff bases, ketimine derivatives, represented by the formula ##STR2## wherein R.sup.1 represents a substituted or unsubstituted aromatic ring selected from the group consisting of phenyl, naphthyl, styryl and a heterocyclic group and R.sup.2 represents an alkyl group having 1 to 8 carbon atoms or a substituted or unsubstituted aromatic ring selected from the group consisting of phenyl, naphthyl, styryl and a heterocyclic group, or R.sup.1 and R.sup.2 may form, when taken together with the carbon atom to which they are attached, a fluorenylidene or indenylidine group, the substituent on the aromatic ring being an alkyl group, a nitro group or a hydroxy group, and a process for producing the above ketimine derivatives which comprises reacting diaminomaleonitrile (hereinafter referred to as DAMN) with an aromatic .alpha.-ketone.
2. Description of the Prior Art
It was well known in the art that DAMN produces Schiff bases upon condensation with various aldehyde compounds or a specific ketone, i.e., d-camphor-10-sulfonate as described in M. P. Hartshorn and J. Vaughan, Chem. & Ind., 632 (1961). Also, it was known that certain pyrazine derivatives can be produced by condensation of DAMN with an .alpha.-diketone or an .alpha.-haloketone as described in E. Cyganeck, W. J. Linn and O. W. Webster, in "The Chemistry of the Cyano Group", ed. by Z. Rappoport, Interscience Publishing Co., London, 1970, p 508. However, the reaction between ketones and DAMN has not yet previously been reported.
In the conventional procedure, DAMM is reacted with a carbonyl compound by heating the reactants in the absence of solvents or in an alcohol solvent without using a catalyst, but it is said that no appreciable reaction occurs between a ketone compound and DAMN under such reaction conditions.